电脑数值控制单元外文文献翻译@中英文翻译@外文翻译

英文原文 Computer Numerical Control Unit Today, computer numerical control (CNC) machines are found almost everywhere , from small job shops in rural communities to Fortune 500 companies in large urban areas. Truly , there is hardly a facet of manufacturing that is not in some way touched by what these innovative machine tools can do . Everyone involved in the manufacturing environment should be well aware of what is possible with these sophisticated machine tools. In this chapter, we will explore the basics of the core of CNC machine tool-CNC unit, showing you much of what is involved with its function, working principles ,hardware configuration and software structure. With so many types of CNC machine tools and CNC units in existence, it is next to impossible for this chapter to be extremely specific about any one particular type .The key concepts allow us to view the main features of CNC unit in more general terms, stressing why things are handled the way they are even more than the specific techniques used with any one particular CNC machine tool. With this broad background , you should be able to easily zero in on any kind of CNC machine tool you will be working with. 1 1 INTRODUCTION Machine controls are divided into two types： numerical control(NC)and computer numerical control(CNC) NC controls have to read the program each time a part is run； they have no means of editing existing programs CNC controls can store and allow editing of loaded programs All machines built today are CNC machines CNC unit is the heart of CNC machine. Nevertheless，in order to aid to understand the working principles of CNC unit， it is necessary that the principles of NC system be introduced firstly 1 1 1 NC system The NC machine can be divided into three basic areas. The first area is the control unit, which processes the commands from the input media. The second area is the drive mechanisms, and the last area is the machine itself The most basic function of any NC machine is automatic， precise， and consistent motion control A11 forms of NC equipment have two or more directions of motion， called axes These axes can be precisely and automatically positioned along their lengths of travel The two most common axis types are linear(driven along a straight path)and rotary(driven along a circular path) Instead of causing motion by manually turning cranks and handwheels as is required on conventional machine tools， NC machines allow motions to be actuated by servomotors under control of the NC， and guided by the part program Generally speaking， the motion type(rapid, linear， and circular)， the axes to move， the amount of motion and the motion rate(feed rate)are programmable with almost all NC machine tools Figure 1 1 shows the makeup of a linear axis of an NC machine Figure 1 1 The makeup of a linear axis of all NC machine An NC command executed within the control (commonly through a program) tells the drive motor to rotate a precise amount of angle The rotation of the drive motor in turn rotates the ballscrew And the ballscrew drives the linear axis A feedback device at the opposite end of the ballscrew allows the control to confirm that the commanded number of rotations has taken place All NC machine tools need numerical data for controlling the relative motion between cutting tool and piece part, the component dimensions normally emanating directly from engineering drawings-the geometric data Other digitized numerical data define feed rates， spindle speeds，tool identification numbers， and miscellaneous functions to perform such operations as tool or work changing， or coolant control-the technological data The combination of all this numerical information in a sequence understood by the machine tools controller is called a part program，and the process of creating the data in a correctly structured format is called programming Numerical controls use standard microelectronic modules that have been developed for computer hardware。 Except for special modules needed in servocontrol circuits， no individual modules are necessary， in contrast to traditional controls， which employ only components tailored to suit one specific control function In modern NC controllers extensive control and calculation tasks are performed by one or more integral microprocessors 。 These are termed computer numerical control system( CNCs ) 1 1 2 CNC system and functions of CNC unit Control systems based on industrial PC(abbreviation for personal computer)are increasingly used in automation technology Machine controls have changed greatly with the “age of the computer” Controls today are“softwired”,which allows greater flexibility in changing and upgrading the computer control In fact， many of machines operating characteristics can be changed by the operator， so that the machine operates the way he she wants it to. Parameter tables in CNC machines today allow each machine to be personalized to the needs of the job to be run The modern CNC machine tool is software driven Simply speaking， computer controls are programmed instead of hard-wired Definition： According to Electronic Industries Association(EIA)， CNC system is a special computer system that is equipped with certain interface circuits and servo drivers， and can do part or a11 the works an NC system do by running the software stored in its memories CNCs have expandable memories that can store large numbers of programs， plus subroutines and correction data。 Sophisticated graphic displays and dynamic simulation have also now become available as a result of the extensive memory capacity being built into current CNCs Within only few years， the capability and efficiency of machine controllers has increased to such an extent that the name“numerical control”is no longer appropriate； “computer numerical control”is more accurately descriptive Generally， CNCs comprises CNC unit， feed motion servo subsystem， spindle servo subsystem and some auxiliary control cells, as shown in Figure 1.2， CNC unit is the core of the whole CNC system It is composed of hardware and software。 The hardware comprising a CNC unit is made up of microprocessors， electronic memory modules， I 0 interfaces， and position control modules， etc CNC software controls all functions of the machine and its efficiency of operation， and manages all local programming at the machine tool and graphic simulation of the cutting process if available The hardware and the software work together to do all functions of CNC unit ， which an ordinary NC system can never do ， such as graphic display HMI(Human-Machine Interface)， system diagnosis， implementing of various complex tool-path controlling and compensation algorithms， intelligent controlling， online programming， and Web communications， etc The main functions and features of CNC unit are described as follows： Figure 1 2 CNC machining system (1)Controlling function (the number of control axes and synchronously control axes) Controlling function indicates the maximum axis-number the CNC unit can control and the number of axes the CNC unit can control synchronously It is also the mare features of CNC machine Axes to be controlled by CNC unit have linear axes and rotate axes, basic axes and auxiliary axes Generally， CNC machine needs only 2 axes to be controlled synchronously In case of double toolslides， four axes are needed CNC milling machine， boring machine, and CNC machine center need 3 or more controlled axes The more the number of Controlled axes, especially the number of axes being controlled synchronously, the more powerful functions of the CNC unit, and the more complex structure of the CNC unit， the more difficulty of programming (2)Preparatory function Preparatory function， also called G function， describes the motion modes of CNC machine The motion modes comprise instructions of basic motions， dwell， plane selections，coordinate system settings， tool compensations， reference point return， fixed operation circles，and metric inch unit transfer， etc According to ISO standard， there are 100 types of Gcodes (from G00 to G99)used in CNC unit， which can be divided into two classes- nonmodal codes (which functions are valid only in the code segment including the codes themselves)and modal codes(which can keep effective before the coming of next Gcode of the same group) For the exact function of each G code used in your machine tools， you must reference your control manufacturers manual to find the list of functions for your machine (3)Interpolation function CNC unit does interpolation by using software realtime calculations Linear interpolation，circular interpolation， helical interpolation， and polar coordinate interpolation will do their best to help CNC unit generate tool track as close to various paths as possible (4)Feed function Feed function uses F (Feedrate designation)to designate the. feedrate to axis The method by which feedrate is programmed varies from one machine type to the next Generally speaking，machining centers only allow the feed rate to be specific in per-minute format(inches or millimeters per minute) ， such as ， F15000 means the federate is 15000 millimeters per minute Turning centers， which have position encoders in their spindles， also allow feed rate to be specified in per-revolution format(inches or millimeters per revolution)that is named synchronous feedrate (5)Spindle function An“S”word is used to specify the spindle speed(in RPM for machining centers). An M03 is used to turn the spindle on in a clockwise(forward)D1a11ner M04 turns the spindle on in a counter clockwise manner M05 turns the spindle off Note that turning centers also have a feature called constant surface speed， which allows spindle speed to be specified in surface feet per minute(or meters per minute) On operation panel， there is a button to turn the spindle on and off， as well as a rheostat to control spindle speed All of these functions are activated manually，through the Manual or Jog mode (6)Miscellaneous function Like preparatory functions， miscellaneous functions(M words， from M00 to M99)allow a variety of special functions Miscellaneous functions are typically used as programmable switches(1ike spindle on off， coolant on off， and so on). (7)Compensation function All types of CNC machine tools require some form(s)of compensation Though applied for different reasons on different machine types， all forms of compensation allow the CNC user to allow for unpredictable conditions related to tooling (8)Enhanced graphic display function CNC unit has a CRT or an LCD displayer to show programs， parameters， various compensation data， coordinates， fault information， menus of conversation programming， part graphs It also can monitor dynamic cutter tool paths while machining (9)Self-diagnosis function In CNC unit， various diagnosis programs are designed to prevent faults occurring or going worse With the aids of self-diagnosis programs， operators can find out the fault and its location in time， so that shorten the time of broken-down (10)Communication function A1l current model CNC controls come with an RS-232-C communications (serial) port. All current model personal computers come with a serial communications port By connecting a properly configured cable to the computer and CNC， the user can command that transmissions of CNC programs take place. (11)Programming function There are three methods of developing CNC programs-Manual programming ，conversational(shopfloor)programming， and CAM system programming 1 1 3 Functional interface between hardware and software in CNC unit As being described above， CNC unit comprises hardware and software， which work together to perform all functions of CNC unit Because that software is logically equivalent to hardware，just like in an ordinary computer system， hardware functions can also be implemented by software in CNC system Hardware and software have different characters Hardware can process in a higher speed than software， but it is more expensive； software is flexible when being designed，but it is a little slow on processing Hence， in a CNC system， the proportion between hardware and software is determined by costperformance of the CNC unit In practice， the functional interfaces between hardware and software are not fixed。 In the earlier NC equipments， all functions were implemented by hardware。 As the developing of computer technology， computer was introduced into numerical control system ， formed so-called CNC system. But the participation of computer are different in different CNC units and in different time. Figure 1.3 show four different kinds of functional interfaces between hardware and software in CNC systems. Figure1.3 中文译文 电脑数值控制单元 今天，计算机数值控制（ CNC）机床几乎随处可见，从农村社区小商店工作，财富 500强企业在大城市地区。真的，几乎没有一个小的制造，是不是有点感动这些创新机床能做的。人人参与的制造环境应该很清楚什么是可能与这些精密的工具机。 在本章中，我们将探讨数控机床的数控装置的核心基础，告诉你什么是参与其功能，工作原理，硬件结构和软件结构。有这么多种类型的数控机床和数控单元的存在，几乎是不可能的这一章是关于任何一个特定类型的非常具体的关键概念。让我们看数控系 统的主要特点在更一般的条件的单位，强调为什么事情的处理他们比使用任何一个特定的数控机床的具体技术更加的方式。在这个背景之下，你可以很容易的在零上的任何类型的数控机床将要和你一起工作。 1.1 引言 机器控制分为两种类型：数控（ NC）和计算机数值控制（ CNC）。数控控制读取的程序每次一部分运行；他们没有编辑现有的 c 控制手段可以存储和允许加载程序编辑。所有的机器建立的今天是数控 c 单元是数控机器的心脏。然而，为了帮助理解数控装置的工作原理，它是必要的，数控系统的原理是首先 介绍了。 1.1.1 数控系统 数控机床可分为三个基本环节。第一区的控制单元，处理命令的输入媒体。第二个区域是驱动机制，和最后一个领域是机器本身。 任何数控机床最基本的功能是自动的，精确的，和数控设备一致的运动 control.a11形式有两个或两个以上的方向运动，称为轴。这些轴可以自动准确定位沿其长度的旅行。最常见的两种类型的线性（驱动轴沿直线路径）和旋转（沿圆形路径）。 而造成运动通过手动转动曲柄和手轮是普通机床，数控机床允许的运动是驱动伺服电机的数控控制下，通过部分程序的引导。一般来说，运动型（快速，线性 ，和圆形），移动轴，运动量与运动速度（进给速度）都是可编程的几乎所有的数控机床。 图 1.1 显示了一个数控机床直线轴的化妆。图 1.1 组成的数控机床直线轴数控指令执行的控制范围内（通常通过一个程序）告诉驱动电机旋转角度的精确量。反过来驱动电机的旋转的滚珠丝杠和滚珠丝杠传动。线性轴。在滚珠丝杠的相对端的反馈装置允许控制来确定所要求的数量的旋转运动的发生。 所有的数控机床需要数值数据控制刀具和零件之间的相对运动，组件的尺寸通常直接从所产生的工程图纸 几何数据。其他数字化数值数据定义的进给率，主轴转速，刀具识别号码，和杂项功能执行的工具或工作变换等操作，或冷却控制 技术数据。在一个序列中的机床控制器理解这一切的数值信息的组合称为程序的一部分，并在正确的结构化的格式创建的数据的过程称为程序设计。 数值控制使用标准微电子已开发的模块，对计算机硬件。除特殊模块，伺服控制电路所需，没有单独的模块是必要的，在对比传统的控制，只采用组件适合一个特定的控制功能。在现代数控控制器广泛的控制和计算任务都由一个或多个微处理器进行积分。这些被称为计算机数控系统（ CNC）。 1.1.2 数控系统和功能的数控单元 基于工业 PC 的控制系统（ 个人计算机的缩写）越来越多地应用于自动化技术。机控制已经发生了很大的变化，“计算机时代”。今天是“软接线”控件，允许更大的灵活性在变化升级计算机控制。事实上，许多机器的操作特性，可由操作员改变，使机器的方式，他她想要工作。今天，在数控机床参数表允许每台机器进行个性化的工作需要运行。现代数控机床的软件驱动。简单地说，计算机控制程序代替硬接线。 定义：根据电子工业协会（ EIA），数控系统是一种特殊的计算机系统，配备一定的接口电路和伺服驱动器，可以部分或全部作品的数控系统的运行做存储在其记忆软件。 数控 系统，可以存储大量的节目可膨胀的回忆，加子程序和校正数据。复杂的图形显示和动态仿真也现在由于广泛的内存容量建成为当前数控系统成为可能。在短短的几年中，能力和机控制器的效率提高到这样的程度，的名字“数控”不再是合适的；“数控”更准确的描述。 一般来说，数控机床包括数控装置，伺服系统进给运动，主轴伺服系统和一些辅助的控制单元，如图 1.2 所示，数控单元是整个数控系统的核心。它是由硬件和软件组成。硬件包括数控单元由微处理器，电子存储模块，我 0 接口，和位置控制模块， c 软件控制机器及其运行效率的所有 功能，并管理所有本地编程时的机床和切削过程中如果可用图形仿真。硬件和软件一起做数控装置的所有功能，一个普通的数控系统可以不做，如图形显示的HMI（人机界面），系统诊断，实现各种复杂的刀具路径控制和补偿算法，智能控制，在线编程 ， 和 网 络 通 信 ， 等 主 要 功 能 和 数 控 单 元 的 特 点 如 下 ： 图 1.2 数控加工系统 （ 1） 控制功能（控制轴数和同步控制轴）控制函数表示的最大轴数数控单元可控制轴的数控单元可控制同步的数量。这也是数控机床的母